•Four protesters died and dozens of protesters and guards were injured in clashes outside the US embassy in Yemen.

•Libya announced four arrests in the attack on the US diplomatic outpost in Benghazi. The alleged role of the arrestees in the attack was unknown.

•A former Navy Seal working as a private security contractor was identified as one of four Americans to be killed in the Benghazi attack, along with Ambassador Chris Stevens, technician Sean Smith and an as-yet unidentified fourth US citizen.

•The White House sought to clarify remarks by President Obama Wednesday that Egypt was neither an ally nor an enemy of the United States. A spokesman said Egypt was a "close partner" with the US and there has been no shift in the relationship.

•US authorities identified Nakoula Basseley Nakoula, 55, as the filmmaker behind the incendiary video tied to the embassy violence. Nakoula, whose whereabouts were unknown, had earlier denied playing a central role in the production of the film.

• In its English-language Twitter feed, the Muslim Brotherhood expressed its concern for members of the US diplomatic corps, but the Brotherhood separately put out calls for a large rally on Friday to protest the anti-Islamic film. It was unclear whether the rally would come together.

Yemeni officials say 4 protesters killed in clashes outside embassy

Four protesters were killed and 11 were injured in clashes Thursday outside the US embassy in Sana'a, according to Yemeni security officials. Twenty-four security guards also were reportedly injured.

CNN reports:

Protesters and witnesses said one protester was critically injured when police fired on them as they tried to disperse the angry crowd

[...]

As evening came, the number of protesters dwindled and tensions began to ease, after a day in which demonstrators breached a security wall and stormed the embassy amid escalating anti-American sentiment.

No embassy personnel were harmed, U.S. officials said.

8.54pm BST

Third American fatality in Libya identified as former Navy Seal

A former Navy Seal working as a private security contractor was one of three Americans killed with Ambassador Chris Stevens in the attack in Benghazi.

Glen Doherty, 42, a Massachusetts native, "was on security detail and he was protecting the ambassador and also helping the wounded’’ when he was killed, according to his sister, Katie Quigly, who spoke to the Boston Globe.

Doherty was interviewed last month by ABC News about his work in Syria. He said he had been hired by the state department to try to locate and destroy shoulder-launched surface-to-air missiles, known as MANPADS, that spread through the country during the war to overthrow Moammar Gadhafi.

Doherty said that he traveled throughout Libya chasing reports of the weapons and once they were found, his team would destroy them on the spot by bashing them with hammers or repeatedly running them over with their vehicles. When ABC News spoke to Doherty in late August, he was enjoying a short time off in California before heading back to Libya just days ago.

The State Department declined to comment on Doherty's involvement in the MANPADS program, but pointed to a previous statement from State Assistant Secretary for Political-Military Affairs Andrew Shapiro in which he said the department was looking at "every possible tool to mitigate the threat."

8.39pm BST

Libya reports arrests in Benghazi attack

Earlier today reports from Libya - including from Hisham Matar in the New Yorker - said Benghazi residents were infuriated that the government in Tripoli had not yet dispatched investigators in the death of Ambassador Chris Stevens and three colleagues. The United States announced it would undertake its own investigation, but agents are still en route.

Now Libya has announced arrests in the case, Christiane Amanpour reports. It was unclear how the arrestees were allegedly involved in the attacks or how many suspects there are.

CNN Natl Security (@natlsecuritycnn)

Libya's PM tells @camanpour that those arrested in the Benghazi investigation are all Libyans

Libyan authorities have made four arrests in the investigation into the attack on the U.S. consulate in Benghazi in which the U.S. ambassador and three embassy staff were killed, the deputy interior minister said on Thursday.

"Four men are in custody and we are interrogating them because they are suspected of helping instigate the events at the U.S. consulate," Wanis Sharif told Reuters.

No sign of filmmaker Nakoula, who may have violated probation

Television cameras are staking out Nakoula Basseley Nakoula's house in Cerros, just outside LA, but no sign of the one-time financial fraudster and occasional blasphemous movie director. Reporters are taking bets on whether he's at home.

If Nakoula breached terms of his 2010 conviction – he pleaded no contest to federal bank fraud charges – which included not using computers or the internet for five years without approval from his parole officer, the police sent to protect him could end up arresting him.

As if this story did not have enough elements there is now a gay porn footnote, courtesy of Tim Dax, a muscle-bound adult film actor who, it turns out, was part of the cast of Innocence of Muslims.

Nakoula has been identified as Coptic Christian. Bishop Serapion, head of the Coptic diocese in southern California, told me the Coptic diaspora had fled persecution in Egypt but would not, and should not, support the ant-Islamic film. "They mock our faith, they insult our Bible but we feel this is not the right way to respond," Serapion said.

Updated at 8.41pm BST

7.59pm BST

A fight to end the fighting at US embassy in Cairo

The journalist and author Ashraf Khalil is at the scene of clashes outside the US embassy in Cairo. The scene he paints muddies a bit the picture of who's enraged at whom:

ashraf khalil (@ashrafkhalil)

Just witnessed a dozen incredibly brave civilians step BETWEEN rocks throwers & riot police to defuse things--1 of them a munaqaba woman!!

Clinton: 'We do not stop individuals from expressing their views'

Here is video of Secretary of State Hillary Clinton condemning the anti-Islam video tied to the violence at US diplomatic outposts.

"To us, to me personally, this video is disgusting and reprehensible. It appears to have a deeply cynical purpose: to denigrate a great religion and to provoke rage. But as I said yesterday, there is no justification, none at all, for responding to this video with violence."

[...]

"We do not stop individual citizens from expressing their views, no matter how distasteful they may be."

White House expands on Obama 'ally' comment: Egypt is 'close partner'

A White House spokesman has elaborated on President Obama's statement Wednesday night that the United States considers Egypt neither ally nor enemy.

The US relationship with the government of Egyptian President Mohamed Morsi is a "work in progress," Obama said in a interview with Univison. "I don't think that we would consider them an ally, but we don't consider them an enemy. They're a new government that is trying to find its way. They were democratically elected. I think that we are going to have to see how they respond to this incident."

White House spokesman now tells Foreign Policy that the president was not signaling any change of status in the relationship since the fall of President Hosni Mubarak.

"I think folks are reading way too much into this," spokesman Tommy Vietor said. "‘Ally' is a legal term of art. We don't have a mutual defense treaty with Egypt like we do with our NATO allies. But as the president has said, Egypt is longstanding and close partner of the United States, and we have built on that foundation by supporting Egypt's transition to democracy and working with the new government."

5.26pm BST

How the attack on the US outpost in Benghazi unfolded

Our multi-media team has produced an interactive guide illustrating how the attack on the US diplomatic outpost in Benghazi unfolded. View it here.

From the Guardian's interactive guide to the Sept. 11, 2012 attack on the US diplomatic outpost in Benghazi, Libya. Photograph: Guardian

5.17pm BST

Romney critique captures contrasts in foreign policy approaches

Whatever you think of Mitt Romney's criticism of the White House, the ensuing debate has laid bare basic differences between the president's approach to foreign policy and what Romney's would be, Molly Ball writes in the Atlantic:

To Obama and his team, the best leadership is cautious, thoughtful, and situationally based. To Romney, true leadership means being at the front of every parade. It means reacting with clarity, certainty and a ringing reiteration of American strength to every crisis, a certainty born of underlying ideals so secure that it is not altered by intervening events or changing facts on the ground.

In this way, Romney's reaction to the current crisis was actually an excellent proxy for his foreign-policy philosophy. He knew what he thought in an instant, where Obama preferred to wait and see. He was not deterred by the way the situation changed overnight; the facts might have been slightly different in the morning, including the small matter of the deaths of four U.S. officials, but Romney's underlying convictions were not.

Romney's Wednesday morning attempt to press his criticism of the president, meanwhile, continued to draw negative reviews from Republican stalwarts.

"I think he's a person who knows a lot about economic issues, and how to make money... that being said... he has not shown that he is a person of original foreign policy thinking," said Wall Street Journal columnist Peggy Noonan. "Romney looked weak today."

Mark Salter, the influential longtime adviser to Sen. John McCain and frequently excoriating critic of the president, said the Romney campaign had responded poorly under pressure:

I understand the Romney campaign is under pressure from some Republicans to toughen its attacks on the president. Four years ago, the McCain campaign was regularly urged to do the same, while at the same time we were unfairly accused by more than a few Democrats and many in the press of inflaming race-based opposition to our opponent. I’m sympathetic to Romney’s predicament.

But this is hardly the issue or the moment to demonstrate a greater resolve to take the fight to the president. Four good Americans, brave and true, have just died in service to their country.

McCain himself praised the administration's message:

John McCain (@SenJohnMcCain)

Just watched an excellent and moving stmt by Sec. Clinton- just the right message and tone.

Romney surrogates who have attempted to defend the candidate have run into trouble. Ohio Sen. Rob Portman went on CBS Thursday morning and, in an embarrassing moment on live television, ended up admitting the he himself did not know that the Cairo embassy statement Romney had criticized was issued before the attack on the embassy.

Updated at 5.20pm BST

4.38pm BST

Doublespeak from the Brotherhood

Ahram Online has an article explaining the background to today's Twitter clash between the US embassy in Cairo and the Muslim Brotherhood (see earlier post).

Basically, the embassy was accusing the Brotherhood of saying one thing in English (expressing sympathy to the US on Twitter) and something else in Arabic on its own website.

Ahram Online points out that one article in Arabic on the Brotherhood's website said: "Egyptians rise to defend the Prophet" and that the Brotherhood, on its website and in its Arabic Twitter feed, was praising the protests and calling for a "million man march" on Friday.

Updated at 5.42pm BST

4.17pm BST

Man behind anti-Islam film seeks to hide his role

The man who made an anti-Islam film tied to deadly violence in Libya and attacks on US diplomatic outposts around the world has attempted to hide his role in the production, the Associated Press reports.

US law enforcement identified Nakoula Basseley Nakoula, 55, as the film-maker behind Innocence of Muslims, portions of which appeared on YouTube, where one clip has been viewed more than one million times.

Nakoula denied he had directed the film, though he said he knew the self-described film-maker, Sam Bacile. But the cellphone number that the AP contacted Tuesday to reach the film-maker who identified himself as Bacile traced to the same address near Los Angeles where Nakoula was located.

...Nakoula denied he had posed as Bacile. Federal court papers filed in a 2010 criminal prosecution against him said Nakoula had used numerous aliases in the past. Among the fake names, the documents said, were Nicola Bacily and Erwin Salameh.

During a conversation outside his home, Nakoula offered his driver's license to show his identity but kept his thumb over his middle name, Basseley. Records checks by the AP subsequently found that middle name as well as other connections to the Bacile persona.

Updated at 4.26pm BST

4.10pm BST

Clinton: Anti-Islam video 'disgusting and reprehensible'

US secretary of state Hillary Clinton issued a sweeping condemnation of the film linked to violent protests outside US diplomatic outposts, calling it "disgusting and reprehensible" but having no grounds for violence.

"Let me state very clearly – and I hope it is obvious – that the United States government had absolutely nothing to do with this video," Clinton said. "We absolutely reject its content and message. America's commitment to religious tolerance goes back to the very beginning of our nation.

A film clip titled Innocence of Muslims has been viewed on YouTube more than one million times. As offensive as the film is, Clinton said, it does not justify violence.

"Violence, we believe, has no place in religion and is no way to honor religion," she said. "Islam, like other religions respects, the fundamental dignity of human beings, and it is a violation of that fundamental dignity to wage attacks on innocence."

Clinton said attacking diplomats was particularly damaging.

“It is especially wrong for violence to be directed against diplomatic missions," she said. "These are places whose very purpose is peaceful to promote better understanding across countries and cultures."

Clinton spoke at the state department in advance of a meeting with Moroccan leaders.

US secretary of state Hillary Clinton delivers a statement on the killing of US ambassador to Libya Christopher Stevens and three staff members. Photograph: Paul J Richards/AFP/Getty Images

Updated at 4.42pm BST

4.08pm BST

Saudi Arabia condemns film – and violent protests

Saudi Arabia condemned has condemned the anti-Muslim film as well as denouncing violent anti-American protests, Reuters reports.

"Saudi Arabia has expressed ... its condolences to the United States of America for the victims of violent actions in Libya that targeted the American consulate in Benghazi," state news agency SPA reported citing a senior official.

The kingdom also denounced what it called an "irresponsible" group which produced the film deemed insulting to the Prophet Muhammad and condemned "the violent reactions that occurred in a number of countries against American interests".

Updated at 4.22pm BST

4.01pm BST

Benghazi in shock as jihadist cell blamed for attack

The mood in Benghazi is one of shock and dismay as a jihadist cell is being blamed for the attack on the consulate, the Guardian’s Chris Stephen reports the city.

Chris said there is a fear that the US and the west will now abandon Libya based on a false impression that it is riddled with extremists.

In a telephone update:

The attack was really unexpected ... and against a man, Chris Stevens, who was a great friend of Benghazi. He had been in the city because he was organising a link up between the city hospitals and some Boston hospitals and the Harvard medical school.

If they thought they would win hearts and minds these attackers have definitely not succeeded.

A Libyan photographer apologised to Chris thinking he was American.

‘I wanted to say how sorry I am, this is not Libya,’ he kept saying. That’s really the mood. They are demanding action and they are upset there’s no sign of any investigation.

There have been two counter demonstrations, both pro-America. People gathered at a hotel where diplomats all stay to vent their anger. To say ‘this is not us, we are not Islamists and we want the Americans here'.

There is an anxiety that America and the west will turn against Libya and abandon them. This was the great anxiety that they would be portrayed in this light [as al-Qaida]. They are thinking that the people doing this want this to come through.

Asked who was responsible for the attack, Chris said:

Islamist brigades have been blamed for previous attacks - the rocket attack on the British ambassador, the attacks on the Red Cross, the UN and the Tunisian consulate.

Who did this one is unclear, but certainly it was a very jihadist crowd that gathered and ransacked the [consulate].

I’ve toured both the compounds, with the landlords, [of] the accommodation block and the consulate. They say it was a very organised attack. It was a battle that went on all night - the bullets and RPG holes are all over the place.

They are talking about a group of about 400 people who first attacked the embassy [consulate] and when the embassy armoured car managed to get out to [the accommodation block]. This armed group followed them and laid siege to this building.

From what I’ve seen there is a lot of devastation and blood on the walls and bullet holes. It looks like a fairly battle.

FBI investigators are expected to arrive tomorrow, but in the meantime there are no crime scene investigations, Chris said.

Journalists and people are allowed to wander around these crime scenes. So you wonder when they turn up how much evidence are they going to be able to collect?

It will fuel tension between Tripoli and Benghazi, if Tripoli ignore it as they have ignored all previous attacks.

Local people say there is a very strong, very determined jihadist cell here. It is very well organised and it has impunity. Every time they have an attack nothing happens, even when they destroyed the British war graves here. This time people are demanding action.

There is an Islamic brigade quartered here and they are vigorously denying [involvement]. They are not denying that they were at the demonstration or that they are anti-American. But they are denying that they took part in this attack. I haven’t found anyone there who was willing to say differently.

The question of jihadist units here is become very moot because this was a very blatant attack. They were obviously not nervous about the local security forces. They had all night to do it. The security forces didn’t appear until dawn.

As Chris mentioned there have been counter-demonstrations in Benghazi to protest at the consulate attack.

Video image of a counter demonstration in Al-Shagara Square, Benghazi to protest Tuesday's attack on the US consulate. Photograph: AP

Updated at 4.08pm BST

3.19pm BST

US embassy in Twitter scrap with Brotherhood

A fascinating public exchange on Twitter between the Egyptian Muslim Brotherhood and the US embassy in Cairo.

It begins with an expression of sympathy from the Brotherhood. The embassy thanks the Brotherhood but suggests it takes a look at its own "Arabic feeds" – adding: "we read those too". The Brotherhood then asks for more details.

Libya attack 'backfired'

Matar, whose novel the In the Country of Men, was shortlisted for the Man Booker prize, said the attack is thought to be the work of ultra-religious groups who have perpetrated similar assaults in Benghazi.

Writing in the New Yorker, he says:

Friends and relatives there tell me that the city is mournful. There have been spontaneous demonstrations denouncing the attack. Popular Libyan Internet sites are full of condemnations of those who carried out the assault. And there was a general air of despondency in the city on Wednesday night. The streets were not as crowded and bustling as usual. There is a deep and palpable sense that Benghazi, the proud birthplace of the revolution, has failed to protect a highly regarded guest.

There is outrage that Tripoli is yet to send government officials to Benghazi to condemn the attacks, instigate the necessary investigations and visit the Libyan members of the consulate staff who were wounded in the attack. There is anger too towards the government’s failure to protect hospitals, courtrooms, and other embassies that have suffered similar attacks recently in Benghazi. The city seems to have been left at the mercy of fanatics.

Hisham Matar.

Updated at 3.19pm BST

2.40pm BST

Yemeni cleric called for protest

Yemeni journalist Naser Araybee told us that today's protests at the US embassy in Sana'a came after a call by the controversial cleric Sheikh Abd al-Majid al-Zindani (see earlier).

When an icon of a society is humiliated it means the society is humiliated itself and it would declare its denunciation of this humiliation and if it did not show its anger, it will loose its dignity.

Muslims have no more precious icon than the Prophet Muhammad and lively Islamic people have expressed their denunciation of the film categorically.

Zindani calls upon "Yemeni people and Arab and Islamic people" to follow "lively Islamic people" and express their protest and anger towards those who mock the Prophet Muhammad.

Support your prophet and declare your wrath, you Muslims, especially you the young men of the Arab revolutions whom hopes are in you and you reveal the will of the Arab people.

Updated at 3.23pm BST

2.01pm BST

Syrian opposition's statement on protests

The opposition Syrian National Council has issued a statement condemning the use of violence to protest about the film:

With deep distress the Syrian National Council watched the insults by a group of American bigots to the messenger of Islam and peace Muhammad peace be upon him. The Council, however, was shocked by the reaction to these insults in the form of murder, burning, and destruction.

We condemn the repeated insults to the noble prophet peace be upon him and are outraged to see them tied to the anniversary of the September 11 attacks by suggesting that there is a connection between the events and the tolerant message of Islam.

As we condemn the insults and consider them an assault on the feelings and beliefs of nearly one fourth of the population of the globe we stress the right of everyone who has been offended to express peacefully their rejection and condemnation of those who perpetrated them. However, the reaction by murder, burning, and destruction is rejected and unequivocally condemned.

The Syrian National Council condemns the killing of the US ambassador and the employees of the US embassy in Libya. This act is rejected and violates Islamic Shari'ah and all conventions of international relations that prohibit any assault on envoys and ambassadors and prohibits holding them responsible for actions committed by their compatriots.

Updated at 2.01pm BST

1.54pm BST

Summary

Here's a summary of events so far today

Yemen

•Hundreds demonstrators stormed the US embassy in the capital Sana'a in protest at an anti-Islamic film following similar protests in Benghazi and Cairo. Security sources said 15 people were injured after police used teargas and gunfire to disperse the crowd. Windows to the embassy building were smashed, while cars and US flags were burned.

Syria

•Syrian rebels and a pro-government group clashed near a Shia shrine on the outskirts of Damascus on Thursday, activists said, killing at least three people. The continuing violence came as new international envoy Lakhdar Brahimi arrived in Damascus for talks with senior members of the Assad regime.

Updated at 1.58pm BST

1.42pm BST

Egypt is neither ally nor enemy, says Obama

The US does not consider Egypt an ally "but we don't consider them an enemy" either, President Obama has said in a TV interview, AP reports.

Speaking on the Spanish-language Telemundo channel, Obama said Egypt has a "new government that is trying to find its way." But he warned that if the Egyptian government takes actions showing "they're not taking responsibility," then it would "be a real big problem".

Updated at 1.49pm BST

1.23pm BST

Libyan Muslim Brotherhood condemns embassy attack

The Libyan Muslims Brotherhood has condemned Tuesday's attack on the embassy which led to the death of the US ambassador.

"We vehemently condemn the attack," the group said in a statement, but it issued a number of caveats. It said freedom of speech should be used to attack religions, and urged western governments to take a tougher line on those who insult Islam.

Updated at 1.49pm BST

1.08pm BST

Two groups involved in Yemen protest

Journalist Benjamin Wiacek, who witnessed the aftermath of the storming of the US embassy in Sana'a, says two groups of protesters were involved.

Benjamin Wiacek (@Nefermaat)

1st group of protesters arrived at #US embassy around 8am, protested peacefully, wanted to start a sit-in in front of building #Sanaa#Yemen

US consulate in Berlin evacuated

Staff have been evacuated from the US consulate in Berlin because of a strange-smelling envelope, AP reports.

Spokeswoman Ruth Bennett said the smell came from an envelope containing supporting materials for a visa application given to consular employees by the applicant in person Thursday morning.

There were no reports of injuries and American and German authorities are now examining the contents.

Updated at 12.57pm BST

12.20pm BST

A clash of bigotries?

In an article for Ahram Online, prominent Egyptian journalist Hani Shukrallah sees a "clash of bigotries" behind the film fracas. He writes:

My first suggestion in this respect is that the makers of the film had deliberately set out to goad Muslims into just such violent and irrational reactions as we have seen in Egypt, Libya and elsewhere.

It's been tested many times before, and even if we can't blame the penchant of certain influential political and ideological forces among us for ignorance and stupidity, we can still argue that those who would set out to trigger such responses are in possession of a very clear manual setting out how to do it, and the broad outlines of expected outcomes.

He goes on to suggest two broader political motives:

America is hurtling towards presidential elections in which Barak Hussein Obama is running for a second term. For large sections of the American Christian right (closely allied to rightwing Zionism), Obama is, if not the anti-Christ, than at the very least a Muslim mole planted in the White House.

For his part, Obama, from the very start of his presidency, had set out to douse the fires of the "clash of civilisations" then still raging courtesy of Messrs Bush and Bin Laden, among others ...

To reignite "the clash" in some form serves to bolster the American Right as a whole, the American Christian Right (which is a mainstay of the Republican Party) specifically, while at the same time undermining Obama ...

He also suggests there is a desire "to tarnish, even to deny the very existence of an Arab spring".

Among the dramatic effects of the historic revolutionary upsurge of the Arab world during the past two years had been a sweeping reimaging of the Arabs before in the eyes of the world at large, including the west ...

There is little doubt that the provocateurs had counted on an irrational and violent reaction and they got it, possibly beyond their most optimistic expectations.

The result is the same: the image of Arabs and Muslims as produced by the Arab spring is painted over with the old racist/Orientalist brush of the clash of civilisations.

'No casualities' in Sana'a embassy protest

Despite reports of heavy gunfire, Yemen's embassy in Washington no casualties were reported when protesters stormed the US embassy compound in Sana'a.

An embassy statement emailed to Reuters said Yemen's government condemned the attack by protesters angry at a film seen as insulting to Islam, adding security forces had restored order at the complex.

The statement said:

Fortunately no casualties were reported from this chaotic incident. The government of Yemen will honour international obligations to ensure the safety of diplomats and will step up security presence around all foreign missions.

Protesters climb a fence at the US embassy in Sana'a September. Yemen's embassy in Washington said no casualties were reported. Photograph: Mohamed al-Sayaghi/Reuters

11.15am BST

Protest in Tehran

About 500 protesters have gathered in Tehran outside the Swiss embassy which represents US interests in Iran, the Zurich-based Tages-Anzeiger newspaper is reporting (in German).

The paper says a large police presence is protecting the embassy building.

The demonstrators are said to be calling for maker of the anti-Muslim film to be killed but are also chanting the customary "Death to the US" and "Death to Israel" slogans.

11.12am BST

Brahimi arrives in Damascus

It's all happening. The new international envoy Lakhdar Brahimi has arrived in Damascus for his first trip to the country since taking up the post.

Brahimi will meet Syrian foreign minister Walid al-Moualem on Thursday and is due to meet President Bashar al-Assad for talks aimed at addressing the conflict.

"During his visit to Syria, Brahimi will hold talks with the government and with representatives of the Syrian opposition and civil society," his spokesman Ahmad Fawzi said in a statement.

Brahimi was accompanied by the Canadian diplomat Mokhtar Lamani, who will remain in Damascus to assume his new functions as head of the office of the joint Arab League-UN mission in Syria.

Updated at 11.14am BST

11.04am BST

'Hundreds' storm US embassy in Sana'a

Yemeni protesters chanted "death to America" and burned the US flag, as hundreds stormed the US Embassy compound in the capital Sana'a, AP reports.

The protesters breached the usually tight security around the embassy and reached the compound grounds but did not enter the main building housing the offices. Once inside the compound, they brought down the US flag, burned it and replaced it with a black banner bearing Islam's declaration of faith: "There is no God but Allah."

Before storming the grounds, demonstrators removed the embassy's sign on the outer wall, set tires ablaze and pelted the compound with rocks.

Yemeni security forces who rushed to the scene fired in the air and used tear gas to disperse the demonstrators and were eventually able to drive them out of the compound. It was not immediately clear whether anyone was inside the embassy at the time of the attack.

The Yemeni embassy in Washington condemned the attack and vowed to ensure the safety of foreign diplomats and to step up security measures around their missions in the country.

Yemeni protesters smash windows of the US embassy in Sana'a. The security forces responded with heavy fire. Photograph: Yahya Arhab/EPA

Updated at 11.21am BST

10.50am BST

Yemen US embassy protest prompted by cleric

Between 10 and 15 demonstrators managed to break into the US embassy in Sana’a after a call to protest by a radical Yemeni cleric, according to Sana’a based journalist Nasser Araybee.

There was very heavy gunfire during the incident he said in a phone interview with the Guardian. Two cars in the embassy compound were burnt and protesters tried to tear down the US flag, Araybee said.

Smoke could be seen from every where. [Initially] we thought it was the building but it was cars that were burned.

There is no one in building now, and security is very heavy. The firing has almost seized.

There are hundreds of protesters outside the building, he added.

Based on reports by three of his friends in the area, Araybee said:

The mood is very very bad. The area is very afraid because of the firing. Many residents told me that children were horrified, because of what they heard. After the saw the smoke a lot of them started to move. Now it is getting quieter and quieter.

He claimed the protests came after Sheikh Abd al-Majid al-Zindani, a religious leader accused by the US of supporting terrorism, called for a protest yesterday.

Zindani called on Yemenis to follow the example of protesters in Libya and Egypt, Araybee said.

Zindani, 70, is one of the most influential religious figures in Yemen as well as a prominent member of the conservative-Islamist Islah party. In 2004 he was listed by the US Treasury as a "specially designated global terrorist".

Protesters storm US embassy compound in Yemen

Protesters have forced their way into the compound of the US embassy in the Yemeni capital, Sana'a, according to numerous reports.

Reuters, citing local witnesses, says:

Demonstrators smashed windows of the security offices outside the embassy before breaking through the main gate of the heavily fortified compound in eastern Sanaa. Security guards opened fire and there were reports of casualties on both sides but no details were immediately available.

AP says that before storming the embassy compound, the demonstrators removed the embassy's sign on the outer wall and set tyres alight. Once inside the compound, they brought down the US flag and burned it.

AP adds that the protesters were on the embassy's grounds but did not enter the building housing the offices.

The Yemen Times reported a few minutes ago that US embassy staff were being moved to a safer location.

They [Morsi and the Muslim Brotherhood] seem far more concerned at the moment with their domestic political interest in protecting their right flank against Salafi outbidding than with behaving like the governing party of a state.

Then Morsi issued a statement condemning the anti-Islamic film and urging the US to sue the film makers. In his first statement on the issue he also failed to condemn the killing of Chris Stevens.

Obama thanked Libyan President Mohamed Magariaf for his condolences over the deaths of US ambassador Chris Stevens and three other state department officers during an assault on the U.S. consulate in Benghazi Tuesday. The White House says the two leaders agreed to work together to bring the attackers to justice.

During a second call, Egyptian President Mohammed Morsi promised Egypt "would honor its obligation to ensure the safety of American personnel," the White House said.

Obama told Morsi that while "he rejects efforts to denigrate Islam ... there is never any justification for violence against innocents."

Security outside the US embassy in Cairo appears to have been stepped up after a second night of protests.

Sources tracking militant Islamist groups in eastern Libya say a pro-al Qaida group responsible for a previous armed assault on the Benghazi consulate is the chief suspect. A senior defence official told CNN the drones would be part of "a stepped-up, more focused search" for a particular insurgent cell that may have been behind the killings.

Some officials drew attention to the scale of the assault, ostensibly over an anti-Muslim film, compared to an earlier protest in Cairo. [But] senior administration officials also said they believe that the consulate building, which was burned and looted, was the intended target, and that Stevens was an accidental victim. The attackers are unlikely to have known the ambassador was visiting from Tripoli.

Stevens had a yearning to mingle with Arabs to get a street level view of events, and he sometimes chafed about the post-September 11 security measures that sometimes prevented diplomats from reaching far into the hinterland.

Egypt

Police vehicles fired teargas at protesters who were banging stones on metal to make noise. Stones were hurled from both sides. An anonymous protester said he demands that the US ambassador to Egypt be expelled and measures against the screening of the film to be taken.